Man page
A man page (short for manual page) is a form of software documentation usually found on a Unix or Unix-like operating system. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts. A user may invoke a man page by issuing the man command. By default, man typically uses a terminal pager program such as more or less to display its output. Man pages are often referred to as an on-line or online form of software documentation, even though the man command does not require internet access, dating back to the times when printed out-of-band manuals were the norm. In the first two years of the history of Unix, no documentation existed. The Unix Programmer's Manual was first published on November 3, 1971. The first actual man pages were written by Dennis Ritchie and Ken Thompson at the insistence of their manager Doug McIlroy in 1971. Aside from the man pages, the Programmer's Manual also accumulated a set of short papers, some of them tutorials (e.g. for general Unix usage, the C programming language, and tools such as Yacc), and others more detailed descriptions of operating system features. The printed version of the manual initially fit into a single binder, but as of PWB/UNIX and the 7th Edition of Research Unix, it was split into two volumes with the printed man pages forming Volume 1. Later versions of the documentation imitated the first man pages' terseness. Ritchie added a "How to get started" section to the Third Edition introduction, and Lorinda Cherry provided the "Purple Card" pocket reference for the Sixth and Seventh Editions. Versions of the software were named after the revision of the manual; the seventh edition of the Unix Programmer's Manual, for example, came with the 7th Edition or Version 7 of Unix. For the Fourth Edition the man pages were formatted using the troff typesetting package and its set of -man macros (which were completely revised between the Sixth and Seventh Editions of the Manual, but have since not drastically changed).
